Although having become increasingly popular, the 3D image is recently made on the basis of the binocular parallax technology. For example, a non-patent document 1 shows a technical explanation regarding the 3D image and a safety guideline regarding the 3D image. The human recognizes image signals generated from two view points, i.e., the right eye and left eye, and thus determines whether an object is stereoscopic or not. The distance of human's right eye and left eye is about 5-7 cm varied from a child to an adult. Therefore, the images accepted by right and left eyes are respectively different because of the viewer's view points. The difference becomes larger when the distance to the object is closer, and becomes smaller when the distance to the object is farther. The brain perceives on the basis of the parallax caused by the both eyes whether the object is stereoscopic or not.
As respectively giving images made from different view points to the right eye and left eye, the viewer can feel the depth of image. The 3D display utilizing the binocular parallax is a technology, which utilizes a 3D eyewear, such as a liquid crystal shutter, and independently and repeatedly gives images to the right and left eyes. For example, when the right eye's image and left eye's image are sequentially arranged on a display based on that principle, the image shown on the display looks like stereoscopic and the human can perceive the stereoscopic image protruding back and forth with respect to the display surface. When the degree of parallax is increased, the back and/or forth protruding amounts become larger. Thus, using the 3D eyewear, such as a liquid crystal shutter, can enhance the impression and surprise to the viewer who is viewing the image.
Some eyewear is commercially available as the 3D eyewear dedicated for the 3D TV, which includes a changing switch for changing from the 3D image to the 2D image. When a viewer wearing the 3D eyewear views the 3D image and have tired eyes, the viewer can double-click the changing switch for forcibly changing the 3D image into the 2D image. When the changing switch is clicked to select the change into the 2D image with the eyewear having the liquid crystal shutter that is utilized for the 3D TV and alternately shows the right eye's image and left eye's image, respective liquid crystal shutters for the left and right eyes open the shutters at the same timing for showing the right eye's image or left eye's image. Thus, the same image can be given to the viewer's both eyes, i.e., the right eye's image or left eye's image.
A patent document 1 shows a stereoscopic-image display apparatus that includes a reflecting member on a frame of a 3D eyewear, and a display device having a means for emitting light and a light receiving means for receiving reflected light, and that receives light reflected from the 3D eyewear to determine whether the 3D eyewear is worn or not and then to change the display from the 3D image to the 2D image. FIG. 6 is a perspective view that shows a schematic configuration of the stereoscopic-image display apparatus in the patent document 1. In this stereoscopic-image display apparatus, the right eye's image and left eye's image are alternately displayed, similarly to the 3D TV described above. The stereoscopic-image display apparatus emits light for detecting the wearing condition, and checks whether or not light reflected from the reflecting member arranged on the frame of the 3D eyewear is received. When having received the reflected light, the stereoscopic-image display apparatus determines that the viewer is wearing the 3D eyewear and continues displaying the 3D image. The viewer wearing the 3D eyewear can view the 3D image. When having not received the reflected light, the stereoscopic-image display apparatus determines that the viewer is not wearing the 3D eyewear. Then, the stereoscopic-image display apparatus generates any one of the right eye's and left eye's images described above, and automatically changes into the 2D image without the viewer's manipulation.